The invention is primarily intended to be usable for cleaning of so-called crankcase gases, i.e. gases formed in a combustion engine, from particles in the form of oil and/or soot. It may alternatively be used in other contexts, such as cleaning of air in various industrial premises in the engineering industry, within the chemical industry or, for example, for cleaning the air around various types of machine tools.
A centrifugal separator of the type indicated in the introduction is known from patent specification SE 515 302 C2, in which each of the conical separation discs, on their inside, have contact with or are connected to elongate guiding means which each extend at an angle with respect to generatrices of the respective separation disc from a point at a first distance from the axis of rotation of the rotor to a point at a larger second distance from the axis of rotation of the rotor. The guiding means—which may also take the form of spacing elements, i.e. guiding means which bridge the interspaces between mutually adjacent separation discs in order to form said interspaces between the separation discs—end in the vicinity of the respective separation disc's circumferential edge at a distance from one another along the circumferential edge. Said guiding means (spacing elements) gather up the separated particles, which are caused to leave the guiding means and are thrown from the separation discs substantially only in limited regions situated at a distance from one another along the circumferential edges of the respective separation discs.
It has been found, however, that separation discs with elongate spacing elements (irrespective of whether the spacing elements are straight and purely radial, are straight and form an angle with the radius or are curved), especially in concurrent flow separation, may have inactive regions on the surface of the separation discs, i.e. regions which make a relatively slight or no contribution at all to the separation of particles from the gas. Such inactive regions occur mainly at the radially outer parts of the interspaces and—depending on the direction of rotation—directly behind or in front of the respective spacing elements as viewed in the direction of rotation. Radially outer parts of the interspaces means in principle the radially outer half of the conical portion of the separation disc. This means that not all of the surface of the separation disc is used for separation of particles, with consequently reduced separation efficiency of the separation disc.